Recent years, in a condensing process of a refrigerant in a refrigeration cycle for use in car air-conditioning systems or the like, the following technique has been proposed. In the technique, after increasing the heat release of the refrigerant by subcooling the condensed refrigerant to lower the temperature than the condensing temperature thereof by a few degrees to obtain a subcooled refrigerant, the subcooled refrigerant is introduced to decompressing means and an evaporator to enhance the refrigeration performance.
In this proposed technique, a heat exchanger with a receiver tank (subcool system condenser) in which a receiver tank is attached to a heat exchanger integrally provided with a condensing portion and a subcooling portion has been developed.
As shown in FIG. 24, in this heat exchanger with a receiver tank, a heat exchanger body 100 includes a pair of headers 101 and 101 and a plurality of heat exchanging tubes disposed in parallel with each other with opposite ends communicated with the headers 101 and 101. The plurality of heat exchanging tubes is grouped into a plurality of passes P1 to P5 by partitions 102 provided in the headers 101 and 101. The passes P1 to P3 constitute a condensing portion 110, and the passes P4 and P5 constitute a subcooling portion 120 independent from the condensing portion 110.
A condensing portion inlet 111 and a condensing portion outlet 112 are provided to the upper and lower portions of the headers 101 and 101 constituting the condensing portion 110, respectively. On the other hand, a subcooling portion inlet 121 and a subcooling portion outlet 122 are formed in the upper and lower portions of one of the headers 101, respectively.
The receiver tank 130 disposed along one of the headers 101 has a receiver tank inlet 131 and a receiver tank outlet 132 communicated with the condensing portion outlet 112 and the subcooling portion inlet 121, respectively.
In this heat exchanger with a receiver tank, the gaseous refrigerant flowed into the condensing portion 110 via the condensing portion inlet 111 is condensed by exchanging heat with the ambient air while passing through each pass P1 to P3 constituting the condensing portion 110. Furthermore, the condensed refrigerant is introduced into the receiver tank 130 through the condensing portion outlet 112 and the receiver tank inlet 131 and once stored therein. Then, only the liquefied refrigerant is led to the subcooling portion 120 through the receiver tank outlet 132 and the subcooling portion inlet 121. The liquefied refrigerant flowed into the subcooling portion 120 is subcooled by the ambient air while passing through the fourth pass P4 and the fifth pass P5, and then flows out of the subcooling portion outlet 122.
In this receiver tank integrated type heat exchanger, as shown in FIG. 25, for example, the receiver tank 130 is usually connected to the heat exchanger body 100 via a joint member such as a block flange 140. That is, the flange 140 of the heat exchanger is integrally provided with a first block 151 joined to the condensing portion outlet 112 of one of the headers 101 of the heat exchanger body 100 and the second block 152 joined to the subcooling portion inlet 121. The first block 151 is provided with an inlet flow passage 141 having one end opened to the flange upper surface and the other end communicated with the condensing portion outlet 112. On the other hand, the second block 152 is provided with an outlet flow passage 142 having one end opened to the flange upper surface and the other end communicated with the subcooling portion inlet 121.
On the other hand, the receiver tank 130 is provided with a lower end closing member 136 having the receiver tank inlet 131 and the receiver tank outlet 132 each communicated with the inside of the receiver tank 130.
The upper portion of the receiver tank 130 is supported by one of the headers 101 via a bracket (not shown) or the like, while the receiver tank inlet and outlet 131 and 132 are communicated with the end of the inlet flow passage 141 and that of the outlet flow passage 142 of the block flange 140, respectively, via joint pipes 145 and 145. In this state the lower end closing member 136 of the receiver tank 130 is secured to the upper surface of the block flange 140 by tightening screws (not shown) inserted in the block flange 140 to the lower end closing member 136.
In a refrigeration system for car air-conditioners in which such a heat exchanger with a receiver tank is applied, in order to effectively utilize a restricted space in a car body as much as possible, it is desired to further reduce the size of the entire system. In addition, in a refrigeration cycle for car air-conditioners, it is desired to enhance the performance to load fluctuations (overcharge toughness) and suppress the performance deterioration with time due to continuous running (deterioration of leakage toughness). In order to achieve the desires, it is desired to widely secure a steady range of refrigerant, i.e., a stability range in a subcooling state of refrigerant relative to an amount of sealed refrigerant.
In the aforementioned conventional heat exchanger with a receiver tank, however, since the lower end closing member 136 of the receiver tank 130 is fixed to the block flange 140 by using screws, it is required for the lower end closing member 136 to have a thickness such that the lower end closing member 136 can be secured to the block flange 140 by using screws. Accordingly, the volume of the receiver tank decreases, which in turn causes a narrow stability range of the subcooling state of refrigerant, an excessive amount of refrigerant, or an insufficient amount of refrigerant. Thus, it was difficult to obtain stable refrigeration performance.
Furthermore, since the receiver tank 130 is secured to the block flange 140 by using screws, it is required to perform troublesome thread-fastening operation, resulting in troublesome/difficult assembling operation.
It is an object of the present invention to provide a heat exchanger with a receiver tank and a refrigeration system capable of solving the problem of the aforementioned conventional technique, obtaining stable refrigeration performance and performing easy assembling operation.
Other objects and advantages of the present invention will be apparent from the following preferred embodiments.